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authorAbhi Das <adas@redhat.com>2019-05-01 00:53:47 +0300
committerAndreas Gruenbacher <agruenba@redhat.com>2019-05-08 00:39:14 +0300
commit8f91821990fd6f170a5dca79697a441181a41b16 (patch)
tree6efd729419e769c9a86681b5a8aca56e6c3e5995 /fs/gfs2/super.c
parentfbb27873f21d5fb9bf556edcaa67e9891636e5d4 (diff)
downloadlinux-8f91821990fd6f170a5dca79697a441181a41b16.tar.xz
gfs2: fix race between gfs2_freeze_func and unmount
As part of the freeze operation, gfs2_freeze_func() is left blocking on a request to hold the sd_freeze_gl in SH. This glock is held in EX by the gfs2_freeze() code. A subsequent call to gfs2_unfreeze() releases the EXclusively held sd_freeze_gl, which allows gfs2_freeze_func() to acquire it in SH and resume its operation. gfs2_unfreeze(), however, doesn't wait for gfs2_freeze_func() to complete. If a umount is issued right after unfreeze, it could result in an inconsistent filesystem because some journal data (statfs update) isn't written out. Refer to commit 24972557b12c for a more detailed explanation of how freeze/unfreeze work. This patch causes gfs2_unfreeze() to wait for gfs2_freeze_func() to complete before returning to the user. Signed-off-by: Abhi Das <adas@redhat.com> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Diffstat (limited to 'fs/gfs2/super.c')
-rw-r--r--fs/gfs2/super.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 6d89d0ecec2a..5b148cf03293 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -973,8 +973,7 @@ void gfs2_freeze_func(struct work_struct *work)
if (error) {
printk(KERN_INFO "GFS2: couldn't get freeze lock : %d\n", error);
gfs2_assert_withdraw(sdp, 0);
- }
- else {
+ } else {
atomic_set(&sdp->sd_freeze_state, SFS_UNFROZEN);
error = thaw_super(sb);
if (error) {
@@ -987,6 +986,8 @@ void gfs2_freeze_func(struct work_struct *work)
gfs2_glock_dq_uninit(&freeze_gh);
}
deactivate_super(sb);
+ clear_bit_unlock(SDF_FS_FROZEN, &sdp->sd_flags);
+ wake_up_bit(&sdp->sd_flags, SDF_FS_FROZEN);
return;
}
@@ -1029,6 +1030,7 @@ static int gfs2_freeze(struct super_block *sb)
msleep(1000);
}
error = 0;
+ set_bit(SDF_FS_FROZEN, &sdp->sd_flags);
out:
mutex_unlock(&sdp->sd_freeze_mutex);
return error;
@@ -1053,7 +1055,7 @@ static int gfs2_unfreeze(struct super_block *sb)
gfs2_glock_dq_uninit(&sdp->sd_freeze_gh);
mutex_unlock(&sdp->sd_freeze_mutex);
- return 0;
+ return wait_on_bit(&sdp->sd_flags, SDF_FS_FROZEN, TASK_INTERRUPTIBLE);
}
/**